Apple just revealed a big way Siri is going to take on Amazon Alexa

In the latest version of WatchOS, Apple is opening up Siri to Apple Watch apps, Apple said.

Specifically, Apple Watch apps related to fitness, payments, rides, and messages will be able to integrate with Siri.

While Siri has been able to book an Uber on an iPhone, that hasn't been possible through the Apple Watch. It's still not possible because the apps haven't been built yet, but the tools for developers to make it happen are now available.

Previously, third-party requests on the Apple Watch would send users to the iPhone to perform those actions. But now they could be completed directly on the Apple Watch.

Siri is one of a few virtual assistants battling for market share. Google has its Google Assistant, and Amazon has a virtual assistant called Alexa that has recently been embraced by hardware makers.

The conventional wisdom is that Amazon is currently winning the race to rule the market for virtual personal assistants.

Google and Amazon have been packing their personal assistant into speakers — Google Home and Amazon Echo — and Apple is rumored to be working on a similar product.

But Apple has the advantage of millions of watches already on people's wrists. The argument is that you don't need a speaker equipped with microphones if there's already something on your wrist. Plus, it's estimated that there are more Apple Watches out there than Amazon Echos.